A two-component protease in Methylorubrum extorquens with high activity toward the peptide precursor of the redox cofactor pyrroloquinoline quinone

Pyrroloquinoline quinone is a prominent redox cofactor in many prokaryotes, produced from a ribosomally synthesized and post-translationally modified peptide PqqA via a pathway comprising four conserved proteins PqqB?E. These four proteins are now fairly well-characterized and span radical SAM activity (PqqE), aided by a peptide chaperone (PqqD), a dual hydroxylase (PqqB), and an eight-electron, eight-proton oxidase (PqqC). A full description of this pathway has been hampered by a lack of information regarding a protease/peptidase required for the excision of an early, cross-linked di-amino acid precursor to pyrroloquinoline quinone. Herein, we isolated and characterized a two-component heterodimer protein from the ?-proteobacterium Methylobacterium (Methylorubrum) extorquens that can rapidly catalyze cleavage of PqqA into smaller peptides. Using pulldown assays, surface plasmon resonance, and isothermal calorimetry, we demonstrated the formation of a complex PqqF/PqqG, with a K-D of 300 nm. We created a molecular model of the heterodimer by comparison with the Sphingomonas sp. A1 M16B Sph2681/Sph2682 protease. Analysis of time-dependent patterns for the appearance of proteolysis products indicates high specificity of PqqF/PqqG for serine side chains. We hypothesize that PqqF/PqqG initially cleaves between the PqqE/PqqD-generated cross-linked form of PqqA, with nonspecific cellular proteases completing the release of a suitable substrate for the downstream enzyme PqqB. The finding of a protease that specifically targets serine side chains is rare, and we propose that this activity may be useful in proteomic analyses of the large family of proteins that have undergone post-translational phosphorylation at serine.National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [GM118117, GM124002, 1S10OD020062-01

Challenges to water quality assessment in Europe – Is there scope for improvement of the current Water Framework Directive bioassessment scheme in rivers?

The EU Water Framework Directive (WFD) assessment scheme has been putting in force the evaluation of freshwater ecosystems in Europe, including a new paradigm of ecological status. After almost 20 years since the WFD implementation, it is imperative to evaluate the efficiency of its standard assessment scheme and to explore the possibility of learning how to improve its effectiveness. That is the spirit of this review, aiming (i) to explore the existing literature on the WFD bioassessment scheme for assessing freshwater ecosystem health, particularly in lotic ecosystems (where the WFD scheme is most consolidated); (ii) to document which paths are suggested by the scientific community to improve the efficiency of the bioassessment in tackling current challenges. In the specific arena of bioassessment, we first identify the major constraints to the WFD full implementation in rivers. Second, we analyse retrospective Ecological Risk Assessment (ERA) as an evaluation approach supporting management actions that could inspire improvements in the WFD bioassessment scheme. Third, we review the advances and debate on complementary metrics to improve WFD evaluation protocols and/or the feasibility of the evaluation outcome. Fourth, a conceptual scheme for an improved evaluation strategy is presented. Our proposal essentially merges the WFD bioassessment scheme with the ERA philosophy, proposing a tiered approach of increasing complexity and spatial resolution, where expert judgement is included surgically at all decision stages. This scheme requires true integration of chemical, ecological and ecotoxicological LoE for a quantitative estimation of risks, and provides a comprehensive framework that accommodates tools and perspectives already suggested by other authors. Besides providing a literature review on the strengths and weaknesses of the current WFD bioassessment scheme, we wish to open way for the scientific discussion towards an improved conceptual scheme for the evaluation of ecosystem health.CESAM - Centro de Estudos Ambientais e Marinhos, Universidade de Aveiro(UIDP/50017/2020 + UIDB/50017/2020

Le Referativnyi Zhurnal, Entomologhia

Ghilarov Merkurii. Le Referativnyi Zhurnal, Entomologhia. In: Bulletin de la Société entomologique de France, volume 88 (1-2), Janvier-février 1983. Livre du Cent Cinquantenaire. Premier congrès international des entomologistes d'expression française. Paris, 6-9 juillet 1982. Comptes rendus des travaux. I. pp. 163-165

Ecology, mythology and the organismic way of thinking in limnology

For laymen, the word 'ecology' has become naturally surrounded with mythological mist. The influence of mythological thinking on ecology as a science is not so evident, but it certainly exists and in some aspects it can hardly be overestimated. The idea of the organism as a model or matrix for shaping new knowledge about populations, communities and ecosystems is extremely important in the maintenance of mythological thinking in modern ecology. We may even consider the organismic ideas as a vehicle of mythology in modern ecology. In this article, the problem is illustrated with limnology - an advanced branch of ecology in which it is easier to see the connections and contradictions between the dominant approaches

Le Referativnyi Zhurnal, Entomologhia

Ghilarov Merkurii. Le Referativnyi Zhurnal, Entomologhia. In: Bulletin de la Société entomologique de France, volume 88 (1-2), Janvier-février 1983. Livre du Cent Cinquantenaire. Premier congrès international des entomologistes d'expression française. Paris, 6-9 juillet 1982. Comptes rendus des travaux. I. pp. 163-165